The present invention relates generally to printers, and more particularly to a method for operating a printer wherein the printer has vertically offset printheads.
Printers include color ink jet printers having black, cyan, magenta, and yellow printheads mounted on a carrier system. Each printhead includes a column of nozzles. The carrier system moves perpendicular to the direction of movement of the print medium. Conventional ink jet printers include those which compensate for vertically offset printheads by enabling only commonly-aligned ones of the nozzles of the printheads, such commonly-aligned ones of the nozzles defining a common print region of the printheads. It is known to operate a printer in a draft mode by printing a raster line in one pass of the printheads and by advancing the paper between raster lines. It also is known to operate a printer in a shingling mode by printing a raster line in several passes of the printheads without advancing the paper between passes and by advancing the paper between raster lines.
What is needed is an improved method for operating a printer.
A first method of the invention is for operating a printer having vertically offset first and second printheads, wherein the first printhead has a first array of nozzles and wherein the second printhead has a second array of nozzles. The first method includes steps a) and b). Step a) includes printing in a first mode which enables a number xe2x80x9cMxe2x80x9d of vertically consecutive nozzles in the first array and which enables a number xe2x80x9cNxe2x80x9d of vertically consecutive nozzles in the second array. Step b) includes printing in a second mode which enables only a number xe2x80x9cmxe2x80x9d of vertically consecutive nozzles in the first array and which enables only a number xe2x80x9cnxe2x80x9d of vertically consecutive nozzles in the second array, wherein xe2x80x9cMxe2x80x9d is greater than xe2x80x9cmxe2x80x9d, xe2x80x9cNxe2x80x9d is greater than xe2x80x9cnxe2x80x9d, and the xe2x80x9cmxe2x80x9d and xe2x80x9cnxe2x80x9d vertically consecutive nozzles define a common print region.
A second method of the invention is for operating a printer having vertically offset first and second printheads, wherein the first printhead has a first array of nozzles printing a first color and wherein the second printhead has a second array of nozzles printing a second color different from the first color. The method includes steps a) through d). Step a) includes advancing the print medium a first distance to a next raster line to be printed in a first mode. Step b) includes printing in the first mode which enables a number xe2x80x9cMxe2x80x9d of vertically consecutive nozzles in the first array and which enables a number xe2x80x9cNxe2x80x9d of vertically consecutive nozzles in the second array. Step c) includes advancing the print medium a second distance to a next raster line to be printed in a second mode, wherein the first distance is greater than the second distance. Step d) includes printing in the second mode which enables only a number xe2x80x9cmxe2x80x9d of vertically consecutive nozzles in the first array and which enables only a number xe2x80x9cnxe2x80x9d of vertically consecutive nozzles in the second array, wherein xe2x80x9cMxe2x80x9d is greater than xe2x80x9cmxe2x80x9d, xe2x80x9cNxe2x80x9d is greater than xe2x80x9cnxe2x80x9d, xe2x80x9cMxe2x80x9d equals xe2x80x9cNxe2x80x9d,xe2x80x9cmxe2x80x9d equals xe2x80x9cnxe2x80x9d, and the xe2x80x9cmxe2x80x9d and xe2x80x9cnxe2x80x9d vertically consecutive nozzles define a common print region.
A third method of the invention is for operating a printer having vertically offset first and second printheads, wherein the first printhead has a first array of nozzles and wherein the second printhead has a second array of nozzles. The method includes steps a) and b). Step a) includes printing a first raster line which enables all of the nozzles in one of first and second arrays when the first raster line does not require printing by the other of the first and second arrays. Step b) includes printing a second raster line which enables only common-print-region ones of the nozzles in the first and second arrays when the second raster line requires printing by both the first and second arrays.
Several benefits and advantages are derived from one or more of the methods of the invention. In one example, printing in a first mode which enables all of the nozzles in the arrays of the vertically offset printheads provides a greater-height raster line such as when printing all raster lines in a draft mode, or when printing a raster line in a quality mode which calls for only one printhead or only aligned printheads. In the same or another example, printing in a second mode which enables only common-print-region ones of the nozzles of the printheads corrects for vertically offset printheads such as when printing all raster lines in a quality mode, or when printing only those raster lines in a quality mode which call for vertically offset printheads. Operating a printer to print in the first and second modes in different print jobs or in the same print job and even on the same sheet of print medium increases the efficiency of the printing operation.